The present invention relates to a method and a circuit for controlling the pressure in wheel brake cylinders of fluid-operated vehicular brakes, wherein a pulse train controlling the associated outlet valve is supplied to the outlet valves associated with the brake cylinders dependent on predeterminable differences between a reference velocity and the velocity of an associated wheel, with the pulse train being variable in response to the deceleration (negative acceleration) or positive acceleration of the associated wheel.
In antiskid systems operating according to this known principle, cases may occur where the pressure decrease in the wheel brake cylinders cannot be ensured in the manner required for reliable operation of the system.
The most frequently occurring case is that a control cycle is initiated at such a low speed that the wheel concerned comes to a standstill before a sufficient pressure decrease could be accomplished. Because the wheel is at a standstill, no further deceleration signals are produced, and as a result no further pressure decrease can take place.
Another undesirable state is the case where the pressure decrease in a wheel brake cylinder attains exactly a magnitude at which the wheel does not continue decelerating while at the same time the wheel has not yet accelerated again sufficiently.